1. Field of the Invention
This invention relates to spray arms and in particular to the manufacture of hollow spray arms from sheet material.
2. Description of the Prior Art
In dishwashers and the like, it has been conventional to provide rotating spray arms for throwing the cleaning liquid in spray jets throughout the space in which the articles to be cleaned are disposed. The spray arms define hollow elements through which the liquid is passed from a suitable impeller. The arms are provided with suitable spray outlets through which the liquid is caused to pass under pressure in the form of spray jets. A number of different configurations for such spray arms have been developed in the art. For example, a spray arm for such use is illustrated in U.S. Pat. No. 2,905,393 of George J. Fedrighi et al. As shown therein, the spray arm is defined by an upper wall and a lower wall cooperatively defining a hollow space through which the washing liquid is passed to the outlet spray openings.
Another form of such a washing system spray arm is illustrated in U.S. Pat. No. 3,288,155 of Norman T. Swetnam.
One method of forming such spray arms has been to form the top and bottom wall thereof from sheet stock, such as sheet metal stock. It has been conventional to stamp elements from sheet stock for further forming operations in forming a number of different devices. Illustratively, in U.S. Pat. No. 1,889,037, William Clarke S. Mays shows the stamping of blanks from a sheet for subsequent formation of writing instrument clips from the blanks. As shown in that patent, the clip blanks are cut from the strips with lace material being left between the respective clip blanks.
George A. Lyon shows, in U.S. Pat. No. 2,168,358, a method of forming an impact member wherein successive blanks are cut from a strip with only a small portion of the blanks being wasted in forming the series of identical impact members.
Where the final formed objects are identical, it has been possible to utilize the entire sheet material without wastage. Thus, as shown in U.S. Pat. No. 1,576,304, of John E. Bryers, implement sockets having a preselected configuration are cut from the stock strip with each portion cut from the strip being formed into an implement socket without further removal of material therefrom.
Similarly, in U.S. Pat. No. 1,819,142, James H. Wily shows a handle connector having blank portions in nested association so as to provide the desired connector structure without wastage from the supply strip.
Stanley B. Elliott shows, in U.S. Pat. No. 3,852,870, a method of producing ornamental articles having a configuration illustrated in FIG. 10 of that patent from blanks cut continuously from a strip without scrap loss in the formation process.
Fred E. Ahlbin discloses in German Pat. No. 1,452,549, published Apr. 3, 1969, a method of manufacturing scissors wherein the two halves of the scissors are formed from a blank cut from a sheet.